tbuckley/cabot-search huggingface dataset:
Abstract P3131: SIRTUIN5 Modulates Na <sup>+</sup> /Ca <sup>2+</sup> Handling Through Oxidative Stress Dependent Mechanism In Mouse Heart
Authors: Jin-Young Yoon, Biyi Chen, Song Ling Sheng, David B Lombard, Barry London
Journal: Circulation Research (2023)

Mutations in cardiac sodium channel Na V 1.5 (encoded by SCN5A) can cause inherited or acquired arrhythmias, including ~20% of cases of Brugada Syndrome (BrS) and inherited conduction disease. The peak Na V 1.5 current (I Na, Peak ) and the late current (I Na, Late ) govern the fast upstroke and plateau of the cardiac action potential, respectively. Ca 2+ ions impact excitation-contraction coupling, and imbalance in Na + /Ca 2+ homeostasis can cause electrical disturbance. BrS is characterized by a right bundle branch block pattern on EKG, arrhythmias, and sudden cardiac death. Recently, potential mutations in SIRT5, including P114T-SIRT5, were identified in small families with BrS. SIRT5 is a member of the Sirtuin family, acts as NAD + -dependent deACYLase.We explored the potential role of SIRT5 in BrS using heterologous expression systems and homozygous P114T-SIRT5 knock-in (P114T-KI) mice. SIRT5 co-immunoprecipitates with Na V 1.5 in HEK293 cells. Live-cell staining using DCFDA or mitoSOX showed that P114T-KI hearts had increased basal reactive oxygen species (ROS) and were more sensitive to oxidative stress induced by H 2 O 2 than wild-type littermates. P114T mice displayed Ca 2+ -mishandling as measured by Ca 2+ imaging in perfused hearts, increased I Na, Late , prolonged QTc, and arrhythmias. Notably, treatment with mitochondrial ROS scavenger mitotempo mitigated the aberrant Ca 2+ handling and arrhythmia in P114T mice.Together, these suggest that P114T-SIRT5 causes Na + /Ca 2+ mishandling-induced arrhythmias in ROS-dependent manner, highlighting potential mechanisms underlying BrS. They pave the way for using SIRT5 or its activators as novel anti-arrhythmic therapies.
Abstract P2049: Myosin Heavy Chain-7 E848G Mutation-induced Sarcopenia And Hypocontractility In Induced Pluripotent Stem Cell Model Of Hypertrophic Cardiomyopathy Are Rescued By Muscle Ring Finger 1 Ablation
Authors: Alexander M Loiben, Clayton E Friedman, Wei-Ming Chen, Kai Chun Yang
Journal: Circulation Research (2023)

Hypertrophic cardiomyopathy (HCM) presents with idiopathic left ventricular hypertrophy and occasionally systolic dysfunction. In a human induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) model of HCM, we previously reported the pathogenic MYH7 E848G variant increased hiPSC-CM size and impaired contractility. To elucidate the mechanisms by which the E848G variant causes HCM, we now examined cardiac tissue from a MYH7 wt/E848G patient. We found reduced expression of the following sarcomeric proteins: β-myosin heavy chain (βMHC) (97.8 ± 1.1% reduction), α-sarcomeric actinin (αSA) (84.8 ± 7.3%), and ventricular myosin light chain (MLC-1v) (45.9 ± 13.9%) relative to healthy patient tissue. Isogenic MYH7 wt/E848G hiPSC-CMs also had reduced protein expression of βMHC (22.8%) and αSA (24.5%) relative to MYH7 wt/wt hiPSC-CMs and unchanged mRNA expression. These results suggest MYH7 E848G HCM induces broad sarcomere component deficiency. We tested hiPSC-CM contractility using single cell traction force microscopy (TFM) and engineered heart tissues (EHT). Single isogenic MYH7 wt/E848G hiPSC-CMs had lower maximum twitch force (80 ± 12 nN) than MYH7 wt/wt hiPSC-CMs (150 ± 20 nN) by TFM. Isogenic MYH7 wt/E848G EHTs had lower maximum twitch force (118.9 ± 23.7 μN) than MYH7 wt/wt EHTs (287.4 ± 27.7 μN). Because MuRF1, an E3 ubiquitin-protein ligase, is known to target βMHC for proteasomal degradation, we hypothesized MuRF1 mediates the sarcopenic and hypocontractile phenotype. Genetic ablation of TRIM63 (encoding MuRF1) significantly reduced MYH7 wt/E848G hiPSC-CM cell size by flow cytometry (6.8 ± 1.7%). MYH7 wt/E848G TRIM63 -/- hiPSC-CMs increased protein expression of βMHC (154.7 ± 51.9%), αSA (44.9 ± 25.6%), and MLC-1v (246.9 ± 57.3%) relative to MYH7 wt/E848G TRIM63 +/+ hiPSC-CMs. MYH7 wt/E848G TRIM63 -/- had significantly higher maximum twitch force by TFM (133 ± 14 nN) and EHTs (178.2 ± 9.8 μN) than MYH7 wt/E848G TRIM63 +/+ by TFM (67 ± 8.0 nN) and EHTs (118.9 ± 23.7 μN). Our results implicate sarcopenia in the pathogenesis of MYH7 E848G HCM and identify MuRF1 as a potential novel therapeutic target for HCM. Further study will determine if these findings are generalizable to other pathogenic HCM variants in MYH7 and other sarcomeric genes.
Abstract P3106: Sex-specific Limitation Of Cardiac Capacity: Return To Fundamental Structure And Function.
Authors: Meihan Guo, Candela Diaz-Canestro, David Montero
Journal: Circulation Research (2023)

Objective: The physiology underlying the sex-specific limitation of cardiac pumping capacity remains unresolved. This study experimentally manipulated the pressure gradient (PG) driving venous return to evidence whether cardiac structure and/or function explain sex differences in cardiac capacity in young and older individuals. Methods: Healthy women and men matched by age and physical activity were included within young ( n =40, age=25±4 yr) and older ( n =55, age=60±8 yr) age groups. Cardiac volumes and output (Q) were assessed via transthoracic echocardiography from moderate to peak exercise under two hemodynamic conditions (‘low’ and ‘high’ PG between lower and upper body) generated via opposite PG identically delivered in a lower body pressure chamber. Main outcomes included sex differences in delta (‘high’ ‘low’ PG) left ventricular (LV) end-diastolic volume (ΔLVEDV), stroke volume (ΔSV) and Q (ΔQ). Results: In young individuals, ‘high’ PG increased exercise LVEDV and SV in men ( P ≤0.002), but not in women ( P ≥0.562), relative to ‘low’ PG. Accordingly, ΔLVEDV, ΔSV and ΔQ were enhanced in young men compared with young women, specifically at the highest exercise intensities ( P ≤0.019). In contrast, right and left atrial volumes were similarly increased by ‘high’ PG in both sexes ( P ≤0.007). ‘High’ PG exclusively prolonged LV filling time during exercise in young men ( P ≤ 0.036). In older women and men, ‘high’ PG did not modify exercise cardiac volumes ( P ≥0.124) and impaired established markers of LV diastolic function ( P ≤0.049). Conclusions: The female young heart is not constrained by venous return or structural factors external to the myocardium. An impaired ability to lengthen LV filling time with augmented venous return may limit female-specific cardiac capacity. With older age, cardiac chambers are not distended and LV diastolic function is impaired with increased PG in both sexes.
Abstract P3134: Impaired Calcium Homeostasis Underlies Lamin A/C Mutation R331Q Associated Atrial Fibrillation
Authors: Aiste Liutkute, Mario Pavez-Giani, Izzatullo Sobitov, Stan van Wijk, Samuel Sossalla, Lukas Cyganek, Bianca J Jjm Brundel, Niels Voigt
Journal: Circulation Research (2023)

Background: Atrial fibrillation (AF) is one of the first cardiac manifestations in patients harboring mutations in nucleoskeletal protein lamin A/C (LMNA). However, the underlying arrhythmogenic mechanisms are unclear. Objective: We hypothesize that impaired intracellular Ca 2+ -homeostasis contribute to LMNA mutation-associated atrial arrhythmogenesis. Methods: LMNA mutation R331Q was introduced in a healthy control induced pluripotent stem cell (iPSC) line using CRISPR/Cas9 and cells were differentiated into atrial iPSC-derived cardiomyocytes (iPSC-CMs). L-type Ca 2+ current and intracellular Ca 2+ concentration were measured using patch-clamp technique and epifluorescence microscopy (Fluo-3), respectively. Results: R331Q iPSC-CMs demonstrated increased L-type Ca 2+ current density followed by increased amplitude of systolic Ca 2+ transient (CaT) compared to isogenic control (Fig. A). Sarcoplasmic reticulum (SR) Ca 2+ content was evaluated from caffeine-induced CaT amplitude and integrated Na + -Ca 2+ exchange current, and found to be greater in R331Q iPSC-CMs (Fig. B). Confocal line scan analysis revealed an increased Ca 2+ spark frequency in R331Q iPSC-CMs (Fig. C). In addition, by applying a stepwise increase in stimulation frequency (1-5 Hz), R331Q iPSC-CMs developed Ca 2+ alternans at lower threshold frequency (Fig. D). Conclusions: LMNA mutation R331Q is associated with disturbed intracellular Ca 2+ cycling, promoting occurrence of diastolic Ca 2+ sparks and arrhythmogenic Ca 2+ alternans. Collectively, our findings suggest that impaired Ca 2+ homeostasis may contribute to atrial arrhythmogenesis in patients harboring LMNA mutations.
Abstract P3013: Rare Case Of Catheter-related Right Atrial Thrombosis In A Pediatric Multi-visceral Transplant Patient
Authors: Akanksha Girish, Niki Noe, Lorenzo De Marchi
Journal: Circulation Research (2023)

Introduction: There has been a recent increase in the use of intraoperative transesophageal echocardiography (TEE) in liver transplant surgeries to identify intracardiac thrombi and pulmonary embolism (PE). These are rare but serious complications of transplant surgery that carry a high mortality risk. However, there is a lack of literature supporting the use of TEE during liver transplants, especially in pediatric cases. Case Presentation: We present a rare case of intraoperative catheter-related right atrial thrombus (CRAT) in a nine-year-old multi-visceral transplant (MVT) patient. This patient’s medical history was notable for preterm birth and gastroschisis complicated by neonatal necrotizing enterocolitis resulting in short-gut syndrome. He had a significant surgical history, including intestinal resection, Hartmann Procedure, and cholecystectomy, after which he developed non-cholestatic liver disease. He was admitted for MVT for intestinal failure associated with ESLD. The procedure was complicated by massive hemorrhage during the dissection phase, significant coagulopathy after engrafting the donor liver, profound hemodynamic instability requiring inotropic drug support, and multiple instances of intraoperative CPR. Intraoperative TEE identified right atrial thrombi around the central venous line. The patient developed RV dysfunction and PEA secondary to PE on two occasions and received a total of 4 mg tissue plasminogen activator (tPA). In both cases, ROSC was achieved after thrombolysis. Due to profound coagulopathy and massive blood loss (70 liters), the completion of the surgery was postponed, and the patient left the operating room with an open abdomen. The patient’s postoperative course was complicated by hemodiafiltration, ureteral resection with reimplantation to bladder, pyloroplasty, appendectomy, small bowel resection, end colostomy and double-barrel ileostomy. The patient eventually developed a subarachnoid hemorrhage on POD3 and expired. Conclusion: This case highlights the importance of utilizing intraoperative TEE in pediatric liver transplant surgeries to diagnose intracardiac thrombi and PE.
Abstract P2133: Preservation &amp; Vascularization Of Cardiac Extracellular Matrix After Acute Myocardial Infarction
Authors: Hong Niu, Zhongting Liu, Ya Guan, Yu Dang, Jianjun Guan
Journal: Circulation Research (2023)

Following myocardial infarction (MI), the upregulated matrix metalloproteinases (MMPs) especially MMP-2/9 lead to the degradation of cardiac extracellular matrix (ECM), leading to impaired cardiac function. Therefore, preservation of cardiac ECM by decreasing MMP-2/9 acitivity will increase cardiac function. Meanwhile, vascularization is critical for cardiac ECM as otherwise its structure and composition change over time. In this work, a non-toxic peptide CTTHWGFTLC (CTT) that specifically inhibits MMP-2/9, and a pro-angiogenic basic fibroblast growth factor (bFGF) were used to preserve and vascularize the cardiac ECM. A fast gelling, degradable, and reactive oxygen species (ROS)-scavenging hydrogel was developed to deliver CTT and bFGF to the infarcted hearts. We evaluated the efficacy of the delivery system in preserving and vascularizing cardiac ECM, and improving cardiac function. The combination of CTT and bFGF synergistically promoted tube formation of HUVECs compared to the treatment with CTT or bFGF (**p&lt;0.01). Interestingly, both CTT and bFGF inhibited myofibroblast differentiation of cardiac fibroblasts. The combination of CTT and bFGF further significantly decreased the differentiation. After 28 days of implantation of the CTT/bFGF/Gel, the wall thickness was significantly increased compared to the CTT/Gel, bFGF/Gel, Gel only and MI. The released CTT and bFGF preserved cardiac ECM, decreased cardiac fibrosis, and stimulated angiogenesis in the infarcted area, leading to a significant increase of cardiac function.
Abstract P1040: An Engineered Human Cardiac Tissue Model Reveals The Potential Contribution Of Systemic Lupus Erythematosus Autoantibodies To Myocardial Injury
Authors: Trevor R Nash, Sharon Fleischer, Manuel A Tamargo, Roberta I Lock, Margaretha Morsink, Vanessa Li, Morgan J Lamberti, Pamela L Graney, Martin Liberman, Youngbin Kim, Richard Z Zhuang, Jaron Whitehead, Richard A Friedman, Rajesh K Soni, Laura Geraldino-Pardilla, Robert Winchester, Gordana Vunjak-Novakovic
Journal: Circulation Research (2023)

A considerable number of patients with systemic lupus erythematosus (SLE) develop myocardial injury. SLE patients have highly heterogenous populations of autoantibodies that may contribute to cardiac disease pathogenesis and heterogeneity; however, little is known about their direct role in myocardial injury. Here, we engineered a model of matured human cardiac tissue and used it to study SLE induced myocardial injury. To this end, we cultured tissues with immunoglobulin G (IgG) from SLE patients with and without myocardial injury. We found that IgG binding levels differed between patient groups and correlated with measures of myocardial inflammation and systolic function. Interestingly, IgG from a subset of patients with systolic dysfunction exerted functional effects on our model system in the absence of immune cells, suggesting a direct contribution to myocardial injury. This was demonstrated by altered calcium handling and cellular composition, impaired cellular respiration, and distinctive patterns of gene expression determined by RNA sequencing. We further harnessed this model to identify potential disease-contributing autoantibodies. We propose that this model can be used to improve risk stratification and therapeutic strategies for SLE patients with myocardial injury.
Abstract P3015: Mechanosensitive, Piezo2 Channels Mediate The Exaggerated Exercise Pressor Reflex In A Mouse Model Of Hind Limb Ischemia.
Authors: qinglu li, Johannes bjorge, An Xie, Satyabrata Das, Samuel C Dudley, Mary G Garry
Journal: Circulation Research (2023)

The exercise pressor reflex (EPR) is a reflexive mechanism in which blood pressure and heart rate increase in response to afferent neuron activation by skeletal muscle contraction. Patients with peripheral artery disease (PAD) have an exaggerated EPR, contributing to exercise intolerance, morbidity and mortality. Recently, we developed a mouse model which we used to determine the effect of femoral artery ligation (FAL) on the EPR. We observed that the EPR is exaggerated 72 hrs following FAL in mice. Stimulation of metabolically active afferent neurons was not different between FAL and control. In contrast, the responses induced by static contraction (stimulation of both mechanically and metabolically sensitive afferent fibers) and passive stretch (preferential stimulation of mechanically sensitive afferent neurons) were exaggerated in FAL mice when compared to control. These exaggerated responses were not affected by SB-705498 (a TRPv1 receptor inhibitor) but were nearly abolished by Gadolinium (a mechanical sensitive group III afferent neuron inhibitor) and significantly reduced by GsMTx-4 (a selective inhibitor of the PIEZO2 receptor).. Furthermore, we observed that PIEZO2 expression was upregulated in the dorsal root ganglia (DRG) from FAL mice compared to controls. Importantly, FAL mice displayed a decreased exercise capacity when compared to control mice, verifying that this mouse model mimics human PAD and supporting the notion that an exaggerated EPR contributes to exercise intolerance. These results further indicate that the exaggerated EPR in FAL is mediated, in part, by the PIEZO2 receptor. To explore this, we generated mice with a conditional, DRG targeted, deletion of Piezo2 . In these mice, we observed that the responses to static contraction and passive stretch were significantly reduced compared to control. Moreover, we performed whole-cell voltage-clamp on dissociated DRG observing increased negative pressure induced inward currents in the setting of FAL while these currents were decreased in the Piezo2 -/- DRG. These data indicate that PIEZO2 expression may serve as a therapeutic target in the treatment of PAD.
Abstract P1161: Interferon Hyperactivity Impairs Cardiogenesis In Down Syndrome Via Downregulation Of Canonical Wnt Signaling
Authors: Kunhua Song, Congwu Chi
Journal: Circulation Research (2023)

Congenital heart defects (CHDs) are very frequent in children with Down syndrome (DS), the genetic condition caused by trisomy of chromosome 21 (T21). Despite significant efforts, the mechanisms by which T21 causes susceptibility to CHDs remain largely unknown. Here, using a combination of a human induced pluripotent stem cell (iPSC)-based model and the Dp(16)1Yey/+ (Dp16) mouse model of DS, we identified downregulation of canonical Wnt signaling downstream of increased dosage of interferon (IFN) receptors (IFNRs) genes on chromosome 21 as a causative factor of CHDs in DS. We differentiated human iPSCs derived from individuals with DS and CHDs (DS/CHD iPSCs), and euploid controls into cardiac cells. We observed that T21 upregulates IFN signaling, downregulates the canonical WNT pathway, and impairs cardiac differentiation. Furthermore, genetic and pharmacological normalization of IFN signaling restored canonical WNT signaling and rescued defects in cardiac differentiation of DS/CHD iPSCs. To define the role of IFN signaling in CHDs in vivo , we genetically and pharmacologically normalized the activity of IFN signaling in the Dp16 mouse model of DS. Normalization of the activity of IFN signaling prevented heart malformations in Dp16 embryos. In addition, treatment with an inhibitor of Janus kinases, which act downstream of IFNRs, normalized canonical Wnt signaling and ameliorated CHDs in Dp16 embryos. Our findings provide new insights into mechanisms underlying CHDs in DS, ultimately aiding the development of novel therapeutic strategies.
Abstract P1076: Rrad Regulates Cardiomyocyte Cell Cycle Entry By Modulating Calcineurin Activity
Authors: Lynn Devilee, Jessica Miller, Qinghui Ou, Abou Bakr M Salama, douglas andres, Jonathan Satin, Tamer Mohamed, James E Hudson, Riham Abouleisa
Journal: Circulation Research (2023)

Background: Cardiomyocytes (CMs) lost during ischemic cardiac injury cannot be replaced due to their limited proliferative capacity, which leads to progressive heart failure. We and others have shown that reduced CM contractility can promote cell cycle induction; however, the underlying mechanisms are still unclear. Calcium (Ca 2+ ), a key regulator of cardiac contractility, is also an important signal transducer that regulates key cellular processes. Ca 2+ enters CMs through the LTCC, which triggers Ca 2+ release from the sarcoplasmic reticulum to initiate CM contractility. The aim of this study is to understand the role of Ca 2+ signaling during CM cell cycle induction. Methods and Results: We performed a drug screening targeting proteins involved in CM calcium cycling in human iPS-derived cardiac organoids. Changes in Ki-67 expression were assessed as an S-G2/M phase marker. The top hit was Nifedipine, an inhibitor of LTCC. To inhibit the LTCC activity, we overexpressed Ras-Related Associated with Diabetes (RRAD), an endogenous regulator of LTCC activity. RRAD overexpression significantly reduced the intracellular calcium amplitude. RRAD overexpression promoted cell cycle induction, increased CM number, and upregulated cell cycle genes in primary neonatal, adult pig, human heart slices, and human iPS-derived cardiac organoids. Moreover, RRAD overexpression significantly augmented the CM response to other cell cycle stimulators such as Cyclin A2, a combination of CDK4 and cyclin D (2F), or a combination of CDK1, CDK4, cyclin D, and cyclin B (4F). Mechanistically, we found that RRAD overexpression reduced the activity of Ca 2+ dependent serine/threonine phosphatase (Calcineurin), as indicated by a significant reduction in calcineurin phosphatase activity in vitro and the expression levels of the calcineurin downstream effectors such as Rcan1 expression as well as translocation of NFAT and Hoxb13 to the CM nucleus. Conclusion: Disruption of Ca 2+ handling by RRAD overexpression promotes cell cycle induction in CMs through modulation of calcineurin activity. Further work in vivo is needed to test whether RRAD overexpression could improve cardiac function after ischemic injury.
Abstract P1077: Transcription Factor Nfya Regulates Mitochondrial Metabolism And Cardiomyocyte Proliferation In The Fetal Heart
Authors: Miao Cui, Svetlana Bezprozvannaya, Tian Hao, Rhonda S Bassel-Duby, Ning Liu, Eric N Olson
Journal: Circulation Research (2023)

We previously identified a neonatal cardiomyocyte population that enters the cell-cycle following injury and disappears as the heart loses the ability to regenerate. These regenerative neonatal cardiomyocytes display a unique transcriptional program regulated by NFYA, a subunit of the trimeric complex Nuclear Transcription Factor Y (NFY) that functions as a pioneer factor to promote cell proliferation. To study whether NFYA is required for cardiomyocyte proliferation, we generated mice with cardiomyocyte-specific deletion of NFYA using alpha-MHC-Cre. NFYA KO mice died before birth; their hearts were smaller in ventricular volumes and developed a distinct cardiac noncompaction phenotype, with hyper trabeculation and reduced cardiomyocyte proliferation. Integration of single-nuclear RNA and ATAC sequencing with spatial transcriptomics identified different embryonic cardiomyocyte subtypes in wildtype and NFYA KO hearts, including those from atria, ventricles, trabeculae, and the conduction system. We found that NFYA deletion reduced the reservoir of immature regenerative cardiomyocytes in the fetal heart and increased the number of trabecular cardiomyocytes. Mechanistically, NFYA deletion reduced the expression of genes regulating oxidative phosphorylation metabolism. The defect in mitochondrial metabolism was further supported by decreased activity of NADH oxidation at mitochondrial membranes and reduced levels of TCA cycle metabolites in NFYA KO hearts. Using chromatin immunoprecipitation and reporter assays, we show that NFYA directly regulates the transcription of those mitochondrial metabolic genes as well as cell-cycle genes in cardiomyocytes, thus providing a transcriptional coupling between mitochondrial metabolism and cardiomyocyte proliferation. Our study identified a previously unrecognized transcriptional control mechanism of metabolic genes controlled by NFYA and highlights the importance of oxidative metabolism during fetal heart development and regeneration.